[gtk] calendar: Fix an uninitialized value

[Matthias Clasen <matthiasc src gnome org>]

commit ab84b17c1a9b39e825dcb11ae4bc86caf8df994f
Author: Timm Bäder <mail baedert org>
Date:   Mon Feb 3 12:06:26 2020 +0100

    calendar: Fix an uninitialized value
    
    Values pased to gtk_widget_measure must be initialized to 0. This failed
    if the header widget of the calendar was invisible.

 gtk/gtkcalendar.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/gtk/gtkcalendar.c b/gtk/gtkcalendar.c
index d7e72535d2..05453f5b51 100644
--- a/gtk/gtkcalendar.c
+++ b/gtk/gtkcalendar.c
@@ -1679,11 +1679,10 @@ gtk_calendar_size_request (GtkWidget      *widget,
   GtkBorder day_padding, day_name_padding, week_padding;
   PangoLayout *layout;
   PangoRectangle logical_rect;
-
   gint height;
   gint i, r, c;
   gint calendar_margin = CALENDAR_MARGIN;
-  gint header_width, main_width;
+  gint header_width = 0, main_width;
   gint max_header_height = 0;
   gint max_detail_height;
   gint inner_border = calendar_get_inner_border (calendar);